It is known that damaged anterior cracked ligaments can be repaired by grafting a portion of patellar tendon, which has been harvested with blocks of bone physiologically bound at each end, between the femur and tibia at the knee joint. The harvested blocks of bone are typically positioned in pre-drilled holes in the femur and tibia.
This method of ligament repair is often a difficult and time consuming operation with consequent concerns about patient comfort and safety. The harvesting of patellar tendon can also itself cause problems for the patient. In many patients the graft tendon is also often not in a suitable physiological condition for use. It is, therefore, desirable to harvest tendon without bone attached and then position the tendon at the required site such that the bone growth fixates the tendon to the bone.
A main requirement for fixation is that the graft tendon be held securely without moving or pistoning within a bone hole.
Current methods for fixation of a tendon include a staple, around which the tendon is positioned prior to the staple being placed within the bone. This method suffers two main disadvantages. Firstly, on the femoral side, the staple is applied to the outer surface of the femur and an extra incision is therefore required. Secondly, because fixation is outside the femur and the tendon lies in a bone tunnel of around 40 mm in length, the elasticity of the tendon allows pistoning under load and so healing to the bone of the tendon graft may fail or be a weak, fibrous healing that allows later loosening.